This is the article about the No Policy roulette wheel from MIT depicting the likely temperature rises under a lack of major policy agreement at Copenhagen this year.

## No-Policy Case

The “roulette” wheel below depicts the MIT Joint Program’s estimation of the range of probability of potential global warming over the next hundred years, assuming a scenario in which “no policy” action is taken to try to curb the global emissions of greenhouse gases.

The face of the wheel is divided into six slices, with the size of each slice representing the estimated probability of the temperature change in the year 2100 falling within that range.

The size of the slice for greater than 7 degrees Celsius warming (shown in red) has a probability of 9%. Or, if stated in another way, that probability has the same likelihood as the “odds” of (about) 1 chance in 11. The slice representing the smallest predicted change, less than 3°C (shown in blue), has a probability of less than 1% (1 in 100 odds).

The median value, that level where there is a 50% chance of falling above or below (even odds) is 5.1°C. The other areas of the wheel have likelihoods of occurring: 3 to 4°C, 12% (about 1 in 8); 4 to 5°C, 30% (almost 1 in 3 odds); 5 to 6 °C, 33% (1 in 3 odds); 6 to 7 °C, 15% (about 1 in 7 odds).

For more technical detail see Sokolov et al., 2009.